APPARATUS FOR MEASURING VIDEO NOISE

摘要

PURPOSE:To make it possible to measure S/N of a system to be measured carring out transmission or image treatment through digitiation even if quantization noise is included, by using a sine wave or a rectangular wave varied in a level as the input signal of the system to be measured. CONSTITUTION:A signal (a) containing a sine wave from a signal generating part 1 is supplied to a system 2 to be measured and a signal (b) containing noise is supplied to a measuring part 3. This input signal (b) is inputted in a synchronous pulse separating circuit 6 to separate a horizontal synchronous signal and, on the basis of this signal, a gate signal (c) is generated in a timing pulse generating circuit 7. On the other hand, the input signal (b) is inputted to a gate circuit 4 to gate only the sine wave which is in turn supplied to a phase synchronous oscillating circuit 5 and the oscillated sine wave (e) is gated in a gate circuit 11 through an amplitude control circuit 9 and a phase control circuit 10. This sine wave (f) free from noise and quantization noise is compared to the signal (b) to be measured in a comparison circuit 12 and a signal (g) comprising only a noise component is displayed by a meter 14 through a root- mean-square converting circuit 13.